According to the HMRC, the rules for overpayment relief are intended to:

give a single route for persons to recover overpayments

bring the claims process into line with self-assessment claims and

align time limits with those for other claims.

Claims for overpayment relief must be made within 4 years of the end of the tax year or accounting period to which the claim relates. A claim for overpayment relief can only be made under certain circumstances.

For example, a taxpayer can only claim overpayment relief if they have not had a reasonable chance to correct their tax liability any other way, by making or amending a self-assessment return or appealing against an HMRC assessment or amendment of their return.

A claim for overpayment relief should be made in writing clearly stating the reason for making a claim, the period to which the claim relates and the reasons why the taxpayer considers that the overpayment or excessive assessment has occurred.